And while there is no doubt these glaciers will melt, the big question is – When? According to one meteorologist, Eric Holthaus, who published the story in Grist a few days ago, if the two glaciers collapse, every shoreline and coastal city worldwide could be inundated with water, leaving hundreds of millions of climate refugees homeless.
One of the big concerns about the two Pine Island Bay glaciers is that they are sitting on solid ground and their ice does not displace the ocean. This means that all the water melting from the two glaciers will be added to the total volume of the world’s seas.
“There’s no doubt this ice will melt as the world warms,” Holthaus writes. “The vital question is when.” It is estimated at this time we would see a sea level rise of about 3.4 meters (11.2 feet). And even though scientists used to think it would take thousands of years for Antarctica’s ice sheets to melt, new evidence suggests this could happen in just a few decades.
Marine ice-cliff instability
Keep in mind that Antarctica is a giant landmass, about half the size of Africa. And before humans started burning fossil fuels, the ice was fairly stable. But humans triggered global warming and an insidious change began to take place in the atmosphere. Now, as more and more carbon dioxide is trapped in the atmosphere, the Earth is heating up.
The evidence points to climate change, and to figure out our present predicament, scientists have looked at the end of the last ice age, about 11,000 years ago, when global temperatures stood at roughly their current levels. The evidence shows the Pine Island Bay glaciers collapsed back then, flooding coastal regions.
Holthaus says this is partially the result of something called “marine ice-cliff instability.” This instability is caused because as the ocean floor gets deeper toward the center of this part of Antarctica, each new iceberg that breaks away exposes taller and taller cliffs. “Ice gets so heavy that these taller cliffs can’t support their own weight. Once they start to crumble, the destruction would be unstoppable,” He wrote.
“The new evidence says that once a certain temperature threshold is reached, ice shelves of glaciers that extend into the sea, like those near Pine Island Bay, will begin to melt from both above and below, weakening their structure and hastening their demise, and paving the way for ice-cliff instability to kick in.”
Unstoppable Ice Collapse
Not every scientist agrees with Holthaus. Those who are concerned refer back to a study published in 2016 by climatologists Rob DeConto at the University of Massachusetts-Amherst and David Pollard at Penn State University. The study was the first to incorporate the latest understanding of marine ice-cliff instability into a continent-scale model of Antarctica.
According to the study, estimates of how high sea levels could rise in this century were significantly higher than previous estimates. Instead of a three-foot increase in ocean levels by the end of the century, six feet was more likely, according to DeConto and Pollard’s findings.
Scientists do agree the science isn’t yet certain. Not enough is understood about the mechanics of glaciers or the physics of ice to be sure. But climate researchers agree the new evidence is pointing in a deeply disturbing direction. “Next to a meteor strike, rapid sea-level rise from collapsing ice cliffs is one of the quickest ways our world can remake itself,” Holthaus says. “This is about as fast as climate change gets.”